// JavaScript Document
jQuery.extend({

	createUploadIframe: function (id, uri) {
		//create frame
		var frameId = 'jUploadFrame' + id;

		if (window.ActiveXObject) {
			//var io = document.createElement('<iframe id="' + frameId + '" name="' + frameId + '" />');
			var io = document.createElement("iframe");
			io.id = frameId;        // io.setAttribute("id", frameId);  --���Ǳ���д��    
			io.name = frameId;    // io.setAttribute("name", frameId);  --���Ǳ���д��
			if (typeof uri == 'boolean') {
				io.src = 'javascript:false';
			}
			else if (typeof uri == 'string') {
				io.src = uri;
			}
		}
		else {
			var io = document.createElement('iframe');
			io.id = frameId;
			io.name = frameId;
		}
		io.style.position = 'absolute';
		io.style.top = '-1000px';
		io.style.left = '-1000px';

		document.body.appendChild(io);

		return io;
	},
	createUploadForm: function (id, fileElementId) {
		//create form 
		var formId = 'jUploadForm' + id;
		var fileId = 'jUploadFile' + id;
		var form = jQuery('<form  action="" method="POST" name="' + formId + '" id="' + formId + '" enctype="multipart/form-data"></form>');
		var oldElement = jQuery('#' + fileElementId);
		var newElement = jQuery(oldElement).clone(true); /*�˴�����bug*/
		jQuery(oldElement).attr('id', fileId);
		jQuery(oldElement).before(newElement);
		jQuery(oldElement).appendTo(form);
		//set attributes
		jQuery(form).css('position', 'absolute');
		jQuery(form).css('top', '-1200px');
		jQuery(form).css('left', '-1200px');
		jQuery(form).appendTo('body');
		return form;
	},

	ajaxFileUpload: function (s) {
		// TODO introduce global settings, allowing the client to modify them for all requests, not only timeout  
		s = jQuery.extend({}, jQuery.ajaxSettings, s);
		var id = s.fileElementId;
		var form = jQuery.createUploadForm(id, s.fileElementId);
		var io = jQuery.createUploadIframe(id, s.secureuri);
		var frameId = 'jUploadFrame' + id;
		var formId = 'jUploadForm' + id;

		if (s.global && !jQuery.active++) {
			// Watch for a new set of requests
			jQuery.event.trigger("ajaxStart");
		}
		var requestDone = false;
		// Create the request object
		var xml = {};
		if (s.global) {
			jQuery.event.trigger("ajaxSend", [xml, s]);
		}

		var uploadCallback = function (isTimeout) {
			// Wait for a response to come back 
			var io = document.getElementById(frameId);
			try {
				if (io.contentWindow) {
					xml.responseText = io.contentWindow.document.body ? io.contentWindow.document.body.innerHTML : null;
					xml.responseXML = io.contentWindow.document.XMLDocument ? io.contentWindow.document.XMLDocument : io.contentWindow.document;

				} else if (io.contentDocument) {
					xml.responseText = io.contentDocument.document.body ? io.contentDocument.document.body.innerHTML : null;
					xml.responseXML = io.contentDocument.document.XMLDocument ? io.contentDocument.document.XMLDocument : io.contentDocument.document;
				}
			} catch (e) {
				jQuery.handleError(s, xml, null, e);
			}
			if (xml || isTimeout == "timeout") {
				requestDone = true;
				var status;
				try {
					status = isTimeout != "timeout" ? "success" : "error";
					// Make sure that the request was successful or notmodified
					if (status != "error") {
						// process the data (runs the xml through httpData regardless of callback)
						var data = jQuery.uploadHttpData(xml, s.dataType);
						if (s.success) {
							// ifa local callback was specified, fire it and pass it the data
							s.success(data, status);
						};
						if (s.global) {
							// Fire the global callback
							jQuery.event.trigger("ajaxSuccess", [xml, s]);
						};
					} else {
						jQuery.handleError(s, xml, status);
					}

				} catch (e) {
					status = "error";
					jQuery.handleError(s, xml, status, e);
				};
				if (s.global) {
					// The request was completed
					jQuery.event.trigger("ajaxComplete", [xml, s]);
				};


				// Handle the global AJAX counter
				if (s.global && ! --jQuery.active) {
					jQuery.event.trigger("ajaxStop");
				};
				if (s.complete) {
					s.complete(xml, status);
				};

				jQuery(io).unbind();

				setTimeout(function () {
					try {
						jQuery(io).remove();
						jQuery(form).remove();

					} catch (e) {
						jQuery.handleError(s, xml, null, e);
					}

				}, 100);

				xml = null;

			};
		}
		// Timeout checker
		if (s.timeout > 0) {
			setTimeout(function () {

				if (!requestDone) {
					// Check to see ifthe request is still happening
					uploadCallback("timeout");
				}

			}, s.timeout);
		}
		try {
			var form = jQuery('#' + formId);
			jQuery(form).attr('action', s.url);
			jQuery(form).attr('method', 'POST');
			jQuery(form).attr('target', frameId);
			if (form.encoding) {
				form.encoding = 'multipart/form-data';
			}
			else {
				form.enctype = 'multipart/form-data';
			}
			jQuery(form).submit();

		} catch (e) {
			jQuery.handleError(s, xml, null, e);
		}
		if (window.attachEvent) {
			document.getElementById(frameId).attachEvent('onload', uploadCallback);
		}
		else {
			document.getElementById(frameId).addEventListener('load', uploadCallback, false);
		}
		return { abort: function () { } };

	},
	handleError: function (s, xhr, status, e) {
		// If a local callback was specified, fire it
		if (s.error) {
			s.error.call(s.context || window, xhr, status, e);
		}

		// Fire the global callback
		if (s.global) {
			(s.context ? jQuery(s.context) : jQuery.event).trigger("ajaxError", [xhr, s, e]);
		}
	},
	uploadHttpData: function (r, type) {
		var data = !type;
		data = type == "xml" || data ? r.responseXML : r.responseText;
		// ifthe type is "script", eval it in global context
		if (type == "script") {
			jQuery.globalEval(data);
		}

		// Get the JavaScript object, ifJSON is used.
		if (type == "json" || type == "text") {

			data = r.responseText;
			var start = data.indexOf(">");
			if (start != -1) {
				var end = data.indexOf("<", start + 1);
				if (end != -1) {
					data = data.substring(start + 1, end);
				}
			}

		}

		// evaluate scripts within html
		if (type == "html") {
			jQuery("<div>").html(data).evalScripts();
		}

		return data;
	}
	
});
